diff --git a/CAvSilhouetteSurfTm.cpp b/CAvSilhouetteSurfTm.cpp
index d931be5..d684a1a 100644
--- a/CAvSilhouetteSurfTm.cpp
+++ b/CAvSilhouetteSurfTm.cpp
@@ -141,25 +141,39 @@ MarchingSquares( const DBLVECTOR& vdGrid, int nStepX, int nStepY, double dStep,
    }
 
   // Recupero i contorni
+   const double MIN_LEN = 0.2 ;
    INTVECTOR vnId ;
    while ( chainC.GetChainFromNear( ORIG, false, vnId)) {
      // creo una composita
       CurveComposite crvCompo ;
-      crvCompo.AddPoint( vBiPnt[vnId[0]-1].first) ;
-      for ( int i = 0 ; i < int( vnId.size()) ; ++ i)
-         crvCompo.AddLine( vBiPnt[vnId[i]-1].second) ;
+      Point3d ptPrev = vBiPnt[vnId[0]-1].first ;
+      crvCompo.AddPoint( ptPrev) ;
+      for ( int i = 0 ; i < int( vnId.size()) ; ++ i) {
+         Point3d ptCurr = vBiPnt[vnId[i]-1].second ;
+        // per evitare difetti a Z con entità corte
+         if ( SqDist( ptPrev, ptCurr) > MIN_LEN * MIN_LEN) {
+            crvCompo.AddLine( ptCurr) ;
+            ptPrev = ptCurr ;
+         }
+      }
      // la chiudo
       crvCompo.Close() ;
      // elimino le parti allineate
-      crvCompo.MergeCurves( 10 * EPS_SMALL, ICurve::APL_STD) ;
-     // eseguo offset a sinistra pari allo step
-      OffsetCurve offsCompo ;
-      offsCompo.Make( &crvCompo, -0.5 * dStep, ICurve::OFF_CHAMFER) ;
-      PtrOwner<ICurve> pCrvOffset( offsCompo.GetLongerCurve()) ;
-      if ( ! IsNull( pCrvOffset)) {
+      crvCompo.MergeCurves( 10 * EPS_SMALL, ANG_TOL_STD_DEG) ;
+     // per test mettere a 1
+      #if 0
          vPL.emplace_back( PolyLine()) ;
-         pCrvOffset->ApproxWithLines( 0.5 * dStep, ANG_TOL_APPROX_DEG, ICurve::APL_STD, vPL.back()) ;
-      }
+         crvCompo.ApproxWithLines( 0, 0, ICurve::APL_SPECIAL, vPL.back()) ;
+      #else
+        // eseguo offset a sinistra pari allo step
+         OffsetCurve offsCompo ;
+         offsCompo.Make( &crvCompo, -0.5 * dStep, ICurve::OFF_CHAMFER) ;
+         PtrOwner<ICurve> pCrvOffset( offsCompo.GetLongerCurve()) ;
+         if ( ! IsNull( pCrvOffset)) {
+            vPL.emplace_back( PolyLine()) ;
+            pCrvOffset->ApproxWithLines( 0.5 * dStep, ANG_TOL_APPROX_DEG, ICurve::APL_STD, vPL.back()) ;
+         }
+      #endif
    }
 
    return true ;
diff --git a/EgtGeomKernel.rc b/EgtGeomKernel.rc
index 83efb02..1a6ea85 100644
Binary files a/EgtGeomKernel.rc and b/EgtGeomKernel.rc differ